Sergio @SergioDemianLerner Jan 19 00:57@jeamick In theory a pure PoW-based cryptocurrency can have 5-sec block intervals if it's miners are not heavily clustered into pools. When miners are clustered into pools then the pool bandwidth consumption increases considerably if the block time gets shorter. Pools generally have a few centralized servers, so increasing the load on these few servers is not good to them. On the other side, this can be a good deterrent from centralized pools to form. Other factor that has to be taken into account is state block rates. A cryptocurrency can have a 5-sec block interval as long as the consensus protocol is "inclusive" or cooperative, which means that uncle blocks are counted towards the accumulated chain work. If the cryptocurrency mining is not inclusive, then there will be huge benefits for centralization.In the case of RSK, we could in the future reduce the block time, however, because RSK processes smart-contracts, and because contract processing cannot be generally pre-processed, RSK has a limitation(where an UTXO like cryptocurrency wouldn't have this limitation). This can be corrected by headers-first block-propagation, and in fact this is something we researched at RSK.